Inside the 1000 hp LS, Dai Yoshihara’s Formula Drift Powerplant

Inside the 1000 hp LS, Dai Yoshihara’s Formula Drift Powerplant

By Mike Kojima

MotoIQ Garage has taken over the development of Dai Yoshihara’s engine program for the last two years from a famous high dollar engine builder. The previous engine had decent power but the reliability was lacking. We were experiencing some sort of engine related issue every few events and halfway through the season, the engine performance would degrade and a fresh engine would need to be installed.

When MotoIQ Garage first tore down the engine, we found a bunch of things that we felt inappropriately speced on the engine regarding clearances and specs on the valvetrain. After looking at what was being run we were confident that we could do better in-house. Starting last year we took over Dai’s engine program setting out to make more power with much greater reliability. Our first iteration of the engine ran very well and went well over a season of brutal Formula Drift abuse with no issues.

We also switched to running 98% ethanol fuel. Alcohol-based fuels are very drying to the valvetrains and cylinder walls and can create a lot of oil dilution. So often alcohol-fueled engines wear a lot faster. Not ours.

For the 2018 season, our goal was to get even better wear and reliability out of the engine to ensure consistent performance throughout the season. If you are interested on what we did, read on!

Dai’s engine is technically not a Chevy because there isn’t a single factory Chevy part in it! The engine is roughly based on the LS engine architecture meaning that the bore spacing, bolt locations, and crank journal diameters are about the same but that’s about it!

The heart of the engine is the block which is made by RHS. It is an aluminum block for light weight. For our turbocharged boost, the RHS has six bolts per cylinder holding down the head instead of 4 like your typical LS. An LS has head sealing problems at about 14 psi of boost or around 800 hp of cylinder pressure. The RHS block has a stiffer reinforced deck and six head bolts per cylinder to eliminate had sealing issues.

The RHS block also has replaceable steel liners are very thick can tolerate quite a large overbore, unlike the stock LS sleeves which can only be honed 0.005″ on an LS1 to 0.020 on an LS3 to clean up the cylinders. We will be running a 4.125 bore on our engine or the same as a stock LS7.

Most importantly the RHS block has a 0.50″ higher deck height which will allow us to run a longer rod even with a longish stroke. The long rod will reduce angularity and side load on the piston skirts and cylinder walls reducing stress and wear. The long rod will also reduce piston speed lowering loads on the piston pin, rod and crank.

The RHS block has a very strong bottom end. Billet steel caps are held in place by 4 ARP studs each.

The block has really thick deep skirts and the main caps are also bolted from the sides to the skirts to really tie the bottom end together for maximum strength and stiffness. Having a rigid bottom end is important for the crank and bearing life. Having the whole block dimensionally stable under load helps ring seal and component life in general.

We chose a Lunati Signature Series Crank with a 4.250″ stroke. The Signature Series Crankshaft is a high quality super strong crank which should do a great job of reliably transferring power in our engine. With a 4.125″ bore and a 4.250″ stroke our engine will have a displacement of 454 cubic inches, a huge displacement for an engine of these small external dimensions.

The crank is made from a non-twist 4340 forged steel blank. 4340 is a high nickel alloy known for its toughness and fatigue resistance. A non-twist forging needs a more expensive die but gives superior grain flow through the part.

The crank also has many design features such as gun drilled mains, lightened rod journals, micropolished journals and a windage reducing contoured wing counterweight profile. The Signature Series crankshaft is Pulsed Plasma Nitride Heat Treated for increased journal strength and durability. The crank has proven to withstand applications well over 1500 horsepower which will work fine for what we want to do.